A rate "lock" or "commitment" is a promise from the lender to freeze a certain interest rate and a specific number of points for you for a certain period during your application process. This means your interest rate cannot get higher during the application process.
Rate lock periods can be various lengths of time, anywhere from 15 to 60 days, with the longer period usually costing more. You can get a longer period for your lock, but in making this choice, will probably have a higher interest rate than you would with a shorter rate lock period
There are other ways to get a good rate, besides opting for a shorter rate lock period. The larger down payment you pay, the better the interest rate will be, since you will have more equity from the start. You can pay points to improve your interest rate for the loan term, meaning you pay more up front. One strategy that is a good option for some is to pay points to bring the rate down over the life of the loan. You will pay more initially, but you'll come out ahead, especially if you keep the loan for the full term.
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